Many electromechanical machines use one or more hydraulic or pneumatic systems for performing tasks associated with an industry such as mining, transportation, agriculture, construction, or power generation. These systems may include a moveable object, such as a rod, piston, or cylinder coupled to a work tool on one end and a chamber on the other. Fluid may be provided in the chamber to extend the moveable object along a linear path, typically for several meters. The fluid may be removed from the chamber in order to retract the moveable object along the same path. In certain situations, the precise position of the moveable object may be required for performing certain tasks and/or for automating certain processes associated with the machine.
In some machines, position identification systems are used to determine an absolute position or location of a moveable object within the chamber. These systems typically include markings, such as barcodes, that are laser-etched or deposited along the length of the moveable object. These markings may be detected by optical sensors positioned within the chamber associated with the moveable object. The sensors may scan a portion of the barcode as it passes across a lens and decode the scanned portion to determine a position associated with the moveable object within the chamber.
The proper operation and accuracy of these identification systems is dependent upon the precision and durability of the markings on the moveable object. For example, over time, markings that are painted or etched onto the surface may wear, making detection by the optical sensors difficult. Furthermore, as the precision required by the position system increases, the size of the markings (and spacing between them) becomes more compact. Thus, in order to provide durable markings that include the small-scale precision necessary for accurate position identification, a laser-encoding system with fine adjustment capability that produces high resolution surface markings, may be required.
One method for providing durable, permanent markings on the surface of a moveable object is described in U.S. Pat. No. 5,632,916 (“the '916 patent) to Lappalainen et al. The '916 patent describes a method for producing marks on a metal surface. These marks may be produced by providing a series of successive laser pulses, each producing a trace on the metal surface. Each trace overlaps a previous trace in order to modify the color of the surface piston rod in order to mark the metal surface.
Although the '916 patent may provide a method for forming durable, wear resistant markings using a laser, it may still be inadequate. For example, the method described in the '916 patent does not provide a controllable mounting apparatus for adjusting of the metal surface with respect to the laser. Thus, the system of the '916 patent may not allow precision-controlled adjustment of the surface with respect to the laser. As a result, should one or more of the laser or the metal surface become misaligned, the system of the '916 patent may not adequately correct the misalignment, potentially leading to erroneous and/or imprecise marking of the metal surface.
The disclosed system and method for laser-encoding information onto moveable objects is directed toward overcoming one or more of the problems set forth above.